Device for repairing damage or providing branchings on existing pipe installations

ABSTRACT

A device for repairing damages or providing branchings on pipes, especially in existing underwater pipe installations, comprises a cylindrical, longitudinally divided muff (1) which is dimensioned to be placed around and clamped to the topical pipe (4) by a clamping means (6), a sealing means (18) being provided between the muff (1) and the surface of the pipe (4). At least one of the muff members (2, 3) is composed of a strong outer layer (10) and a less strong inner layer (11) which layers are joined so as to form an intermediate closed volume (14 and 15), said muff member (2 or 3) being provided with a means (17) for supplying a hydraulic pressure medium (19) to said volume, so that the volume when pressurized expands and the inner layer (11) and the sealing means (18) thereby are pressed to seating engagement with the adjacent surface of the pipe (4).

The invention relates to a device for repairing damages or providingbranchings on pipes, especially in existing underwater pipesinstallations, comprising a cylindrical metal muff which islongitudinally divided to form a pair of metal muff members which aredimensioned to be placed around and clamped to the topical pipe by aclamping means, a sealing means being provided between the muff and thesurface of the pipe.

Repair of damages on existing underwater pipe installations, for examplein the offshore industry, may become very expensive. At larger depthswelding is of little current interest since one can not use divers formaking good possible faults arising when using automatic weldingmachines. Today, if a deep-water pipe installation is subjected to crackformation or other minor damages, one will have to remove parts of thepipe and install a jointing means. Known jointing means are complicated,time-consuming and expensive to have installed.

Further, within the offshore industry, there is an expressed wish to beable to make branchings on existing pipe installations without having tointerrupt the operation ("hot tapping"). Secondarily, it is wanted thatsuch operations be executed with the shortest possible operational losson the pipes.

It is an object of the invention to provide a device enablingsubstantial savings in case of repairs of damages on existing underwaterpipe systems, in that damages can be repaired without replacing parts ofthe pipe system.

Another object of the invention is to provide such a device which alsoenables a quick and cost-efficient provision of branchings on existingpipe installations without interruption of the operation, and withoutweakening the pipe installation.

For the achievement of the above-mentioned objects there is provided adevice of the introductorily stated type which, according to theinvention, is characterized in that at least one of the muff members iscomposed of a strong outer layer and a less strong inner layer which arejoined so as to form an intermediate closed volume, said muff memberbeing provided with a means for supplying a hydraulic pressure medium tosaid volume, so that the volume when pressurized expands by movement ofthe inner layer, and the inner layer and the sealing means thereby arepressed to sealing engagement with the adjacent surface of the pipe.

In the device according to the invention, said at least one muff memberwith its outer and inner layers consists of metal, and the sealingdevice consists of metal ribs projecting from and forming closed loopson the surface of the inner layer, for the provision of a metal-to-metalseal between the muff member and the topical pipe.

The device according to the invention when used as a pipe repairingsystem, may give substantial savings, one being able to repair damageswithout replacing parts of the pipe system. Further, one may makebranchings on existing pipe installations without having to interruptthe operation (hot tapping), and without weakening the pipeinstallation. In offshore applications one can, as compared to existingalternatives, nearly irrespective of water depth carry out hot tappingvery quickly and cost-efficiently by using a remotely operated vehicle(ROV) for carrying out the branching operation.

When the hydraulic pressure medium is pressed in between the outer andinner layer of the muff members when the device is assembled on a pipe,there is established a strong pressure pressing the outer layer radiallyoutwards and the inner layer inwards against the pipe. The hydraulicsealing pressure preferably may be permanently maintained in that ahardening liquid is used as the hydraulic pressure medium.

The sealing action is enhanced in that the inner layer 30 is providedwith outwardly projecting, seal-forming ribs, as mentioned above. Thepressurization of the hydraulic pressure medium thereby will entail thatthe material of the ribs reaches the yield point and "melts" togetherwith the surface of the pipe already at a moderate pressure, so that agas-tight metal-to-metal contact is obtained.

A substantial advantage of the present device is that one can obtain asignificant reinforcement of the pipe installation where the muff ismounted, mechanical stresses being "absorbed" by the strong outer layerof the muff. Another important property of the device is that thesealing forces increase with the internal pressure of the pipe, since ahigh pressure will seek to expand the pipe which is thereby pressed evenharder against the inner layer of the muff.

The invention will be further described below in connection withexemplary embodiments with reference to the drawings, wherein

FIG. 1 shows a cross-section of an embodiment of a branching muffaccording to the invention, wherein the components are shown separatedfrom each other;

FIG. 2 shows a cross-section of the branching muff in FIG. 1 inassembled condition;

FIG. 3 shows a cross-section of a ready assembled and pressurized repairmuff;

FIG. 4 shows a cross-section of a repair muff which is provided with aseparate, divided sealing sleeve;

FIG. 5 shows a cross-section of the sealing sleeve in FIG. 4; and

FIGS. 6 and 7 show cross-sections of another embodiment of a repair muffaccording to the invention, in open condition and closed condition,respectively, clamped on a pipe.

In the embodiments in FIGS. 1-5 corresponding members are designated bythe same reference numerals.

The embodiment shown in FIGS. 1-2 comprises an essentially cylindricalmuff or sleeve 1 which is divided in the longitudinal direction for theformation of two halves 2 and 3 which are dimensioned to be placedaround and clamped to the outer surface of a pipe 4, the inner surfaceof the halves having a curvature essentially corresponding to thecurvature of the outer surface of the pipe. Such as appears from FIG. 2,an interspace or gap 5 is left between the adjacent side edges of thehalves 2, 3 when these are placed in their mounting position on the pipe4, to achieve a certain dimensional tolerance and to facilitate theassembly and clamping of the muff or sleeve members on the topical pipe.In the illustrated embodiment, the muff members are clamped by means ofa pair of schematically shown locking clamps 6 which are adapted toengage in longitudinal grooves 7 at the side edges of the muff members.However, it is clear that many different shapes of clamping devices maybe used, for example as shown in the embodiment in FIGS. 6 and 7.

The illustrated embodiment of the device is constructed for providing aleakage-proof branching on a pipe, and for this purpose one muff half 2is provided with a pipe socket 8 projecting from an opening 9 in themuff member, a sealing means being arranged around the opening, such asdescribed below.

As it appears, each of the muff members consists of a relatively thickand strong outer layer 10 and a relatively thin and less strong, innerlayer 11, the two layers being joined--e.g. by welding--along outerlimiting edges of the inner layer, in the illustrated case along the endedges (not shown) of the layers 10, 11 and along their side edges 12,and further along a limiting edge 13 of the inner layer 11 around theopening 9 for the pipe socket 8. Thus, between the inner and outerlayers of the muff halves there are formed respective closed volumes 14and whereby these volumes admittedly has a minimal radial extension, theadjoining surfaces of the inner and outer layers 10, 11 as shown beingclosely adjacent to each other. Each of the muff members is providedwith a short tube length 16 and 17, respectively, extending through theouter layer 10 into the closed volume 14 and 15, respectively, for thesupply of a suitable hydraulic pressure medium for expansion of saidvolume, such as described below.

At the inner surface of the inner layer 11 of the muff member 2containing the pipe socket 8, there is arranged a sealing means which,in the illustrated embodiment, consists of ribs 18 projecting from thesurface and forming closed loops around the joining edge 13, andaccordingly around the pipe socket opening 9. The outer and inner layersof the muff member and the sealing ribs 18 preferably consist of ametal, such that an efficient metal-to-metal seal is formed between themuff member and the topical pipe, when also the pipe is of metal.

Such as will be clear, both muff members 2, 3 may be provided with abranching pipe socket, if desired. When only one muff member has a pipesocket, as in the illustrated embodiment, the other muff member normallywill be without any seal-forming ribs (or a possible other sealingmeans).

Even if the sealing means in the illustrated embodiment consists ofloop-forming ribs formed integrally with the inner layer of the muffmembers, it will be clear that, instead, there may be arranged aseparate sealing means, for example a suitable gasket or packing means.

When installing the shown device, the two muff halves 2, 3 are placedaround the pipe 4 whereafter the locking clamps 6 are fastened.Thereafter hydraulic pressure medium 19 is pressed into the closedvolume 15 through the tube 17, so that the outer layer 10 with expansionof the volume 15 is pressed radially outwards, and the inner layer 11 ispressed inwards against the pipe 4. The tube 17 is shut off when thedesired "locking pressure" is established. The locking pressure, whichmay be of the order of 200 bars, causes a high tractive force in thesleeve member 2 to the left in the Figures, which member is therebypulled tightly against the surface of the pipe 4. Thereafter sealing issecured in the contact surfaces between the ribs 18 and the pipe 4 bypressing pressure medium into the volume 14 through the tube 16 which isshut of f when the desired locking pressure is obtained. In thissituation the ribs 18 will represent closed loops of which each forms abarrier which prevents leakage after an aperture has been formed in thepipe 4 for communication with the pipe socket 8.

As mentioned in the introduction, the pressure medium preferably is ahardening material, e.g. a liquid resin, for maintaining a permanentsealing pressure after injection of the material.

The branching pipe 8 in its extension advantageously may be providedwith a pair of ball valves in series (not shown), to enable locking-inand locking-out of a suitable hydraulic tool which may be used to forman aperture into pipe systems which is wholly or partly in operation(so-called hot tapping).

As appears, the joining edge 13 represents a considerably larger openingthan the pipe socket opening 9. This is due to the fact that one doesnot want the strong sealing pressure to influence the pipe 4 in theregion closely adjacent to the opening 9.

FIG. 3 shows an embodiment of a ready mounted device according to theinvention for repair and mending of damages on existing pipes. Thisembodiment corresponds to the embodiment in FIGS. 1-2, except for thefact 1) that there is not provided any branching pipe socket, and 2)that both of the inner layers 11 of the muff halves 2, 3 are providedwith a sealing means in the form of ribs 18 forming closed loops on theinner surfaces of the layers. This means may be used to seal leakages asa consequence of e.g. crack formations in the topical pipe, providedthat the damage is located within one or more liquid barriers (closedribs). Simultaneously, the means will reinforce the pipe and counteracta further development of the damage.

The sealing means of the device is activated in the same manner as inthe device according to FIGS. 1 and 2, except for the fact that bothsleeve halves 2, 3 now are to be pressurized simultaneously.

In the embodiment according to FIG. 3, one will not be able to establisha seal in the interspace area under the locking clamps 6. However, forthe provision of a seal approximately around the entire circumference ofthe repair muff, there may be arranged a separate inner sealing sleeve,for example as shown of FIG. 4 where the sealing sleeve is designated by20. In relation to the embodiment in FIG. 3, the inner radius of therepair muff is here increased with the thickness of the sealing sleeve.

As shown in FIG. 5, the sealing sleeve 20 consists of a pair ofcylindrical halves 21, 22 having generally semicircular cross-sectionalshape, wherein the halves overlap each other in the joint regions 23, asshown in FIG. 4. The inner diameter of the composite sealing sleeve 20corresponds to the outer diameter of the topical pipe. Both halvesinternally are provided with closed rib patterns 24 wherein the longestrib loops follow the outer edge of each of the sealing sleeve halves. Toensure an optimum sealing action, the orientation of the sealing sleeverelative to the muff halves 2, 3 should be as shown in FIG. 4. In otherrespects the need for sealing ribs in the repair muff itself is reducedwith the use of such a sealing sleeve.

Another embodiment of the repair muff according to the invention isshown in FIGS. 6 and 7. The main difference in relation to theembodiment in FIG. 3 is that the muff halves 25, 26 here are notseparate members, but are permanently connected in a rotating connection27. More specifically, the muff halves at adjacent longitudinal edgesare hinged to each other by means of an axle or hinge bolt 28, whereasthe members, at the opposite longitudinal edges, are provided with ameans for releasable clamping of the muff members around the topicalpipe 29. The clamping means is shown to consist of a locking bolt 30which is adapted to be introduced in mating holes 31 at the free ends ofthe muff halves.

In other respects, the construction in principle corresponds to theaforementioned embodiment according to FIG. 3, each of the muff halves25, 26 consisting of an outer strong layer 32 and an inner less stronglayer 33, wherein the layers are joined to each other along outerlimiting edges 34 of the inner layer, for defining closed volumesbetween the adjacent surfaces of the layers. For the supply of pressuremedium to respective ones of these volumes, there are arranged supplytubes 35 and 36, respectively.

In the illustrated embodiment, only one muff half 25 is provided withloop-forming sealing ribs 37 on the inner surface of the inner layer 33.Further, supporting blocks 38 are shown to be fixed to the inner side ofeach of the outer layers 32 outside of the limiting edges 34, forabutment against the surface of the topical pipe 29 in the diametricallyopposite regions wherein the muff members are attached to each other ininstalled position on the pipe.

As appears from the Figures, the inner layer 33 on the muff member 25 isshown to be substantially thicker than the inner layer 33 on the muffmember 26. This is due to the fact that the first-mentioned layer isprovided with sealing ribs 37 and then must be sufficiently thick totransfer the sealing force to the sealing ribs without yielding, whereasthe other inner layer in the illustrated embodiment is without sealingribs, and then may be relatively thin, for efficient transfer of thesealing pressure from the pressure medium 39.

When mounting the device, the muff half 25 is placed on the topical pipe29 so that the pattern of ribs 37 covers the damage 40 on the pipe.Thereafter the other muff half 26 is pivoted about the hinge bolt 28,and the clamping means is locked in that the bolt 30 is moved in place.The device, which is symmetric about the line A--A in FIG. 7, ispressurized through the supply tubes 35, 36. Whether both, or only onesupply line is to be pressurized, will depend on pipe dimension, type ofdamage, etc. The essential thing is that one achieves a satisfactorypressure with the entire contact surface between ribs and pipe.

The advantages of this embodiment in relation to the embodimentaccording to FIG. 3, is that the device is simpler to position on thetopical pipe, and that an equally large strength is achieved with asmaller total weight of the repair device.

We claim:
 1. A device for repairing damage or providing branchings on apipe, especially in existing underwater pipe installations, comprising acylindrical metal muff which is longitudinally divided to form a pair ofmetal muff members which are dimensioned to be placed around and clampedto the pipe by clamping means, and sealing means provided between themuff and the surface of the pipe, wherein at least one of the muffmembers comprises a strong outer metal layer and a less strong innermetal layer, which layers are joined so as to form an intermediateclosed volume between said strong outer metal layer and said less stronginner metal layer, said muff member being provided with means forsupplying a hydraulic pressure medium to said volume, so that the volumewhen pressurized expands by movement of the inner layer, and the innerlayer and the sealing means thereby are pressed to sealing engagementwith the adjacent surface of the pipe.
 2. A device according to claim 1,wherein the muff comprises two halves which are permanently hinged toeach other at adjacent longitudinal edges, and which at oppositelongitudinal edges are provided with means for releasably clamping themuff members around the pipe.
 3. A device according to claim 2,comprising a separate, longitudinally divided sealing sleeve which isdimensioned for placement between the inner layers of the muff membersand the pipe, the sealing means being disposed on the inner surface ofthe sealing sleeve.
 4. A device according to claim 1, wherein thesealing means comprises ribs projecting from and forming closed loops onthe surface of the inner layer.
 5. A device according to claim 1, forproviding a leakage-proof branching on a pipe, wherein one muff memberis provided with a pipe socket projecting outwardly from an opening inthe muff member, said sealing means being disposed around the opening.6. A device according to claim 5, wherein the sealing means comprisesmetal ribs forming closed seal-forming loops around the opening.
 7. Adevice according to claim 1, wherein the hydraulic pressure medium is ahardenable liquid.